any other species. The black-rimmed yellow eyes seem particularly dazzling against the white face, and the feet are as thickly feathered as you would expect for an animal that lives most of its life in the snowy Arctic. In addition to its unique coloration, the Snowy Owl is one of the most sexually dimorphic of owls. Mature males are almost totally white, with the exception of a few dusky spots on the crown and dusky barring on the tips of the flight feathers, but the larger females are more heavily marked, with dark brown spotting and barring on the crown and upper parts, the flight feathers, tail feathers, and flanks. Despite their markings, however, females still appear predominantly white.
Although long placed in the Bubo genus, along with eagle owls and the Great Horned Owl, many taxonomists today assign the Snowy Owl to its own genus, Nyctea. Whatever the taxonomy, its white plumage and thick feathering are both adaptations to life in the Arctic—just like the similar adaptations of the Arctic fox (Vulpes lagopus), snowshoe hare (Lepus americanus), and rock ptarmigan (Lagopus muta). It ranges right across the Arctic regions of both the Old and New Worlds, but despite this wide distribution, the Snowy Owl is a monotypic species, with only one race recognized.
This bird is nomadic, moving south when conditions become too harsh or the rodent population crashes. In North America, this means heading into southern Canada and the northern United States, with some birds traveling as far as Texas and Georgia. In Eurasia, the wintering quarters extend to Kazakhstan, Mongolia, and northern China. Young males make the longest journeys and older females the shortest. Long-distance travelers may make a series of stop-offs as they head south, defending a temporary territory in each. The Snowy Owl’s nomadic existence means that it moves between different habitats. Its tundra breeding grounds comprise largely treeless terrain, coated with mosses and lichens and punctuated with boulders and patches of snow that remain throughout the summer. Moving south in winter, it exchanges this barren terrain for lake shores, marshes, coastlines, and fields.
A diurnal predator, the Snowy Owl is active between dawn and dusk. On its breeding grounds, it is often seen perched on small tundra mounds or flying low from one perch to the next. Its flight is powerful, with deliberate rowing beats of its long wings and long glides in between. The main hunting strategy is sit and wait: the owl scans the open tundra and then, when a target is spotted, attacks in a long, shallow glide. Voles and lemmings—the small rodents that breed prolifically during the Arctic summer—are its principal prey. It may also take larger mammals, such as snowshoe hares, and targets birds, including ducks and geese, taking them in flight or from the water’s surface. In addition, it may use those sharp talons to pluck fish from the water.
A male Snowy Owl arrives at the tundra nest with his prey.
The Snowy Owl is seldom monogamous. Its changing terrain and long journeys mean that it often finds itself setting up a new territory with a new partner, although pairs have been known to stick together for up to five years. During courtship, the male calls with a booming “hoo hoo”— up to six repeated notes—to which the female responds with harsher, higher calls. He backs up his vocal performance with an impressive display, flying in undulating circles with exaggerated moth-like wingbeats, then descending to bow and strut on the ground, feathers fluffed out, tail cocked, and wings drooping or held up like an angel’s. The nest is made on the ground; there is little choice in the Arctic tundra. A site is chosen that is free from snow and in a productive hunting area, with a good view of the surrounding landscape. The female uses her feet to scrape a shallow depression on top of an elevated mound, which she then lines with a little vegetation and a few feathers.
The clutch size of the Snowy Owl varies from an average of five to eight eggs to an astonishing fourteen or more in peak lemming years. The female lays her eggs at two-day intervals, then incubates them while the male brings food and stands guard. During this period, the parents toil hard. The growing chicks eat two lemmings per day, and a single family may consume up to 1,500 lemmings before the young disperse. Meanwhile, the male defends the nest vigorously. The open terrain means that approaching enemies are easily visible, and the owls have been known to attack Arctic foxes at least 0.6 miles (1 km) away from the nest. If an intruder breaches the male’s defenses, the female will attempt to lure it away with a distraction display. The owls do not hunt immediately around their nest. This means that birds such as the snow goose (Chen caerulescens), which might otherwise be prey, often nest near the owl in order to gain its protection from foxes and other nest raiders.
Numbers of Snowy Owls fluctuate wildly, according to prey availability: the birds become locally abundant in a boom year, then almost disappear the next. Their greatest threat may be climate change, which in bringing about the slow “greening” of the Arctic tundra in some areas may deprive the Snowy Owl of the very habitat for which it is so beautifully evolved.
Snowy Owls may make use of farmland during their winter journey south.
A male Snowy Owl passes food to the female while the youngsters look on.
The heavy dark barring on this Snowy Owl, plus its greater size, identifies it as a female.
A female Snowy Owl taking flight reveals feet that are more thickly feathered than in any other owl species.
The Snowy Owl approaches prey in a low glide, often hidden by the contours of the ground until the last, fatal moment.
The facial markings of the Boreal Owl give an impression of permanent surprise.
BOREAL/TENGMALM’S OWL
AEGOLIUS FUNEREUS
APPEARANCE
Small, with large head and cat-like face; dark marks above eyes and bumps on facial disk give expression of surprise; coloration varies from reddish-brown to gray; upper parts dark with white spots; under parts pale and streaked; in flight, shows short tail and broad wings.
SIZE
length 8.7 – 10.6 in. (22 – 27 cm)
weight 3.3 – 7.6 oz (93 – 215 g)
wingspan 20 – 24 in. (50 – 62 cm)
female much larger than male
DISTRIBUTION
Northern coniferous belt in Old and New World; in North America, from east to west coast, and down the Rocky Mountains to New Mexico; in Eurasia, from Scandinavia to Pacific coast; isolated populations in central Europe, w including southern France.
STATUS
Least Concern
“SURPRISED” IS A TERM COMMONLY USED to describe the facial expression of this small owl. The dark markings above its bright yellow eyes and the two bumps atop its facial disk convey a certain raised-eyebrows astonishment. You might be surprised, too, if you manage to spot one. This nocturnal bird inhabits deep woods and is very wary of people.
The Boreal Owl—known in Europe as Tengmalm’s Owl, after Swedish naturalist Peter Gustaf Tengmalm—is the size of a starling. It does not have true ear tufts but, when alarmed, compresses its facial disk to produce two bumps. The dark upper parts are boldly spotted in white (hence the Finnish name “pearl owl”) and pale under parts are streaked with arrowheads, providing excellent camouflage at its tree trunk roost. Females are much larger than males, showing the most extreme sexual dimorphism